Respiratory Distress and Failure

Disorders of respiration in newborn infants can be categorized as either central nervous system (CNS) failure, representing depression or failure of the respiratory center, or peripheral respiratory difficulty, indicating interference with the alveolar exchange of oxygen and carbon dioxide. Cyanosis occurs in both groups (see Table 92-1). Respiratory problems encountered in the delivery room are most frequently those of airway obstruction and depression of the CNS (maternal medications, asphyxia) with an absence of adequate respiratory effort. Respiratory distress in the presence of good respiratory effort should lead to an immediate consideration of the underlying cause and is an indication for radiographic examination of the chest.

If respiratory movements are made with the mouth closed but the infant fails to move air in and out of the lungs, bilateral choanal atresia (Chapter 368) or other obstruction of the upper respiratory tract should be suspected. The mouth should be opened, and the mouth and posterior of the pharynx cleared of secretions with gentle suction. An oropharyngeal airway should be inserted, and the source of the obstruction sought immediately. If effective respiratory flow is not produced by opening the infant’s mouth and clearing the airway, laryngoscopy is indicated. With obstructive malformations of the mandible, epiglottis, larynx, or trachea, an endotracheal tube should be inserted; prolonged endotracheal intubation or tracheostomy may be required. Respiratory failure caused by CNS depression or injury may require continuous mechanical ventilation.

Hypoplasia of the mandible (Pierre Robin, DiGeorge, and other syndromes; Chapters 300 and 303) with posterior displacement of the tongue may result in symptoms similar to those of choanal atresia and may be temporarily relieved by pulling the tongue or mandible forward or placing the infant in the prone position. A scaphoid abdomen suggests a diaphragmatic hernia or eventration, as does asymmetry in contour or movement of the chest or a shift of the apical impulse of the heart; these latter manifestations are also compatible with tension pneumothorax. A pneumothorax can be the presenting symptom in infants with pulmonary hypoplasia, renal malformations, or both.

Pulmonary causes of respiratory difficulty are discussed in Chapter 95.

Failure to Initiate or Sustain Respiration

Failure to initiate or sustain respiratory effort is common at birth. Infants with primary apnea respond to stimulation by establishing normal breathing. Infants with secondary apnea need ventilatory assistance. Secondary apnea usually originates in the CNS as a result of asphyxia or peripherally because of neuromuscular disorders. Prematurity alone is seldom a causative factor, except in infants weighing <1,500 g. Intrapulmonary problems, such as respiratory distress syndrome, pulmonary hypoplasia associated with oligohydramnios as in Potter syndrome or neuromuscular diseases, bilateral pleural effusions (hydrops fetalis), pneumothorax, and severe intrauterine pneumonia, may at times result in poor ventilation despite strong respiratory efforts. The lungs in affected infants may be noncompliant, and efforts to begin respirations may be inadequate to initiate sufficient ventilation.

Narcosis results from administration of morphine, meperidine, fentanyl, barbiturates, or tranquilizers to the mother shortly before delivery or from maternal anesthesia given during the 2nd stage of labor. This sequela should be avoided by the use of appropriate analgesic and anesthetic practices. Treatment includes initial physical stimulation and securing of a patent airway. If effective ventilation is not initiated, artificial breathing with a bag and mask must be instituted. At the same time, if the respiratory depression is due to an opiate, naloxone hydrochloride (Narcan), 0.1mg/kg, should be given intravenously or intramuscularly. Naloxone is contraindicated in infants born to mothers with opiate addiction because it precipitates acute neonatal withdrawal with severe seizures. If depression is due to other anesthetics or analgesics, artificial respiration should be continued until the infant is able to sustain ventilation. CNS-stimulant drugs should not be used because they are ineffective and may be harmful. External cardiac massage, correction of acidosis, and circulatory support with drugs may be important adjuncts to ventilation in the severely asphyxiated infant.

Neonatal Resuscitation

Although the majority of babies undergo a smooth physiologic transition and breathe effectively after delivery, 5-10% require active intervention to establish normal cardiorespiratory function. The goals of neonatal resuscitation are to prevent the morbidity and mortality associated with hypoxic-ischemic tissue (brain, heart, kidney) injury and to reestablish adequate spontaneous respiration and cardiac output. High-risk situations should be anticipated from the history of the pregnancy, labor, and delivery and identification of signs of fetal distress. Infants who are born limp, cyanotic, apneic, or pulseless require immediate resuscitation before assignment of the 1-min Apgar score. Rapid and appropriate resuscitative efforts improve the likelihood of preventing brain damage and achieving a successful outcome.

Guidelines for neonatal resuscitation propose an “integrated” assessment/response approach for the initial evaluation of an infant, consisting of simultaneous assessment of infant color, general appearance, and risk factors. The fundamental principles include evaluation of the airway, establishing effective respiration and adequate circulation; the guidelines also highlight the assessment and response to the neonatal heart rate and the management of infants with meconium-stained amniotic fluid.

Immediately after birth, an infant in need of resuscitation should be placed under a radiant heater and dried (to avoid hypothermia), positioned with the head down and slightly extended; the airway should be cleared by suctioning, and gentle tactile stimulation provided (slapping the foot, rubbing the back). Simultaneously, the infant’s color, heart rate, and respiratory effort should be assessed (Fig. 94-1).

Figure 94-1 Newborn resuscitation algorithm. CPAP, continuous positive airway pressure; ET, endotracheal; HR, heart rate; IV, intravenous; PPV, positive pressure ventilation.

(From Perlman JM, Wyllie J, Kattwinkel J, et al: Part 11: Neonatal resuscitation: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations, Circulation 122:S517, 2010.)

The steps in neonatal resuscitation follow the ABCs: A, anticipate and establish a patent airway by suctioning and, if necessary, performing endotracheal intubation; B, initiate breathing by using tactile stimulation or positive-pressure ventilation with a bag and mask or through an endotracheal tube; C, maintain the circulation with chest compression and medications, if needed. Steps to follow for immediate neonatal evaluation and resuscitation are outlined in Figure 94-1 (Chapter 62).

If no respirations are noted or if the heart rate is <100 beats/min, positive pressure ventilation is given through a tightly fitted face bag and mask for 15-30 sec. In infants with severe respiratory depression that does not respond to positive-pressure ventilation via bag and mask, endotracheal intubation should be performed. Many authorities recommend early intubation for extremely low birthweight (ELBW) preterm infants. Guidelines for endotracheal tube size and depth of insertion in infants with different birthweights are shown in Table 94-1. If the heart rate does not improve after 30 sec with bag and mask (or endotracheal) ventilation and remains below 100 beats/min, ventilation is continued and chest compression should be initiated over the lower third of the sternum at a rate of 120 beats/min. The ratio of compressions to ventilation is 3:1. If the heart rate remains <60 beats/min despite effective compressions and ventilation, administration of epinephrine should be considered. Persistent bradycardia in neonates is usually due to hypoxia resulting from respiratory arrest and often responds rapidly to effective ventilation alone. Persistent bradycardia despite what appears to be adequate resuscitation suggests more severe cardiac compromise or inadequate ventilation technique. Poor response to ventilation may be due to a loosely fitted mask, poor positioning of the endotracheal tube, intraesophageal intubation, airway obstruction, insufficient pressure, pleural effusions, pneumothorax, excessive air in the stomach, asystole, hypovolemia, diaphragmatic hernia, or prolonged intrauterine asphyxia.